Novel detection methods for biophotonics sensing
thesisposted on 29.03.2022, 01:10 by Piotr Maciej Wargocki
The appearance or increase of the fluorescent signal in biological media (whether it is natural autofluorescence or fluorescence of artificially introduced fluorophores) can implicate reaction to specific conditions or diseases. In the first part of this thesis, we explored the possibilities of using smart phone as a point‐of‐care readout device that could replace specialised laboratory equipment like a spectrophotometer or colorimeter at a fraction of the cost. We present two methods that, using the minimum of additions to the phone itself, are sensitive enough to be used in medical diagnostics of clinically relevant conditions including arthritis, cystic fibrosis and acute pancreatitis. In the second part, we developed the highest resolution wide field Fluorescence Lifetime Imaging (FLIM) system based on a Single Photon Avalanche Diode sensor array. The device was capable of detection of sub‐nanosecond lifetimes over an area of about 20cm2, and was able to measure lifetimes of fluorescent signals lower than one photon per pixel per excitation pulse. We proved that the system can reliably distinguish between biologically relevant concentrations of free and bound forms of Nicotinamide Adenine Dinucleotide (NADH). An increment of bound NADH in cells, which is connected to increased cell metabolism, is a proven cancer marker for most cancer types. We characterised the system performance and provided two methods of data analysis appropriate for measurements in a biological tissues or surface tumours. We project that our system is suitable for development into a realtime fluorescence lifetime camera, able to operate at up to 20 Hz with presented performance level.